Fuel Pump Relay/Fuel Pump Test

Fault Symptom.
Engine fails to start.

Diagnostic Help.
The output stage for activation of the fuel. pump relay is monitored by the Motronic system. See diagnostic trouble codes P1501, P1502, P1541.





Diagnostic Procedure.
1. Check the fuses
- Check that the following fuses are intact:
^ MAXI fuse 2 (+30 circuit, main pump relay power supply)
^ 32 (fuel pump relay's power supply for the fuel pump relay).

Are the fuses intact?
YES: Continue with point 2.
NO: Change the fuse and start the engine. Check whether the fuse blows. If it does, continue with point 6.

2. Check the performance of the fuel pump
- Forcibly actuate the fuel pump by connecting a jumper lead between fuses 4 and 32.

The fuel pump should start working.

Is the pump working?
YES: Continue with point 3.
NO: Continue with point 5.





3. Check the current applied to the pump relay
- Unplug the pump relay.
- Connect a test lamp to pin 30 of the relay socket and a good ground.

The test lamp should light up.

Did the lamp light up?
YES: Continue with point 4.
NO: Check and if necessary repair or replace the lead between pin 30 of the relay socket and crimped connection J93.





4. Check the fuel pump relay
- Connect a jumper lead between pins 30 and 87 of the relay socket.
- Listen for the sound of the fuel pump working.

Is the fuel pump working?
YES: Change the fuel pump relay.
NO: Check and if necessary repair or replace the lead between pin 87 of the relay socket and fuse 32.





5. Check the fuel pump

- Unplug connector H2-9 from the fuel pump. The connector is located adjacent to the fuel pump under the rear seat.

Note that the connector with the two thick cables is the right one. The other is connected to the level sensor.
- Connect the test lamp to pins 1 and 2 of the 2-pin male connector.
- Select "ACTIVATE"
- Connect the ISAT Scan Tool.
- Turn the ignition switch to the ON position.
- Select "FUEL PUMP RELAY".

The test lamp should flash at a frequency of 1 Hz (once per second).

Test lamp flashing?
YES: Check and if necessary change the fuel pump or the wiring harness between H4-7 and H2-9.
NO: First check and if necessary repair or replace the lead between pin 2 and grounding point G3 and then the lead between pin 1 and fuse 32.





6. Check the fuel pump
- Unplug connector H2-9 from the fuel pump. The connector is located adjacent to the fuel pump under the luggage compartment floor.
- Change fuse 32.
- Connect the ISAT Scan Tool.
- Turn the ignition switch to the ON position.
- Select "ACTIVATE".
- Select "FUEL PUMP RELAY".

Did the fuse blow?
YES: Check and if necessary repair or replace the wiring between fuse 32 and pin 1 of connector H2-9.
NO: Change the fuel pump.